Outcomes of a new dosage regimen of amikacin based on pharmacokinetic parameters of Korean neonates

Purpose. Study results indicating improved neonatal amikacin therapy outcomes through the use of a dosage regimen tailored to population-specific pharmacokinetic parameters are presented. Methods. In a retrospective analysis, outcomes of amikacin therapy were evaluated in two groups of Korean neonates: group 1 (n = 107), who received amikacin according to standard neonatal dosing recommendations and empirical dosing guidelines, which often resulted in a need for dosage adjustments; and group 2 (n = 74), who were treated under a revised dosage regimen derived from pharmacokinetic data on group 1 and taking into account unusually high interpatient variability in amikacin clearance among Korean newborns relative to Caucasian populations. The influences of postconceptional and postnatal age on amikacin pharmacokinetics were also evaluated. Results. Relative to standard and empirical amikacin dosing, the revised dosage regimen resulted in a significantly higher percentage of neonates achieving peak concentrations within the target range of 20-30 mg/L (81.3% in group 2 versus 50.7% in group 1, p < 0.001). The percentage of neonates with a peak concentration of <20 mg/L was significantly lower in group 2 (3.8%) versus group 1 (21.6%, p < 0.001), as were the proportion of neonates with peak concentrations of >30 mg/L (15.0% versus 27.6%, p < 0.001) and the need for dosage adjustment by a pharmacist (31.6% versus 59.7%, p = 0.056). Conclusion. A new amikacin dosing regimen based on the pharmacokinetic parameters of Korean neonates was effective in achieving peak and trough amikacin concentrations within the target range.